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답안 #273527

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
273527 2020-08-19T05:44:13 Z 문홍윤(#5110) Mountains and Valleys (CCO20_day1problem3) C++17
2 / 25
 23 ms 13312 KB 
#include <bits/stdc++.h>
#define eb emplace_back
#define mp make_pair
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define svec(x) sort(x.begin(), x.end())
#define press(x) x.erase(unique(x.begin(), x.end()), x.end())
using namespace std;
typedef long long LL;
typedef pair<int, int> pii;
typedef pair<LL, LL> pll;
typedef pair<int, LL> pil;
typedef pair<LL, int> pli;
const LL llinf=2e18;
const int inf=1e9;

int n, m;
vector<int> link[500010];
vector<pair<pii, int> > edg;

int dis[500010], sp[500010][30], ans;

void dfs(int num, int par){
    dis[num]=dis[par]+1;
    sp[num][0]=par;
    for(auto i:link[num]){
        if(i==par)continue;
        dfs(i, num);
    }
}
int lca(int x, int y){
    if(dis[x]>dis[y])swap(x, y);
    for(int i=20; i>=0; i--){
        if(dis[y]-dis[x]>=(1<<i))y=sp[y][i];
    }
    if(x==y)return x;
    for(int i=20; i>=0; i--){
        if(sp[x][i]!=sp[y][i]){
            x=sp[x][i];
            y=sp[y][i];
        }
    }
    return sp[x][0];
}
int get_dist(int x, int y){return dis[x]+dis[y]-2*dis[lca(x, y)];}

int dis2[500010];
void dfs2(int num, int par){
    dis2[num]=dis2[par]+1;
    for(auto i:link[num]){
        if(i==par)continue;
        dfs2(i, num);
    }
}

int main(){
    scanf("%d %d", &n, &m);
    for(int i=1; i<=m; i++){
        int a, b, c;
        scanf("%d %d %d", &a, &b, &c);
        a++; b++;
        if(c==1){
            link[a].eb(b);
            link[b].eb(a);
        }
        else edg.eb(mp(a, b), c);
    }
    dfs(1, 0);
    for(int j=1; j<=20; j++){
        for(int i=1; i<=n; i++)sp[i][j]=sp[sp[i][j-1]][j-1];
    }
    dfs2(1, 0);
    int r1=max_element(dis2+1, dis2+n+1)-dis2;
    dfs2(r1, 0);
    int r2=max_element(dis2+1, dis2+n+1)-dis2;
    ans=2*(n-1)-dis2[r2]+1;
    for(auto i:edg){
        int d=get_dist(i.F.F, i.F.S);
        if(d<=i.S)continue;
        int nd=2*(n-2)+i.S;
        int r1to1=get_dist(r1, i.F.F)+dis2[r2]-1-get_dist(r2, i.F.F);
        int r1to2=get_dist(r1, i.F.S)+dis2[r2]-1-get_dist(r2, i.F.S);
        if(r1to1>r1to2)swap(i.F.F, i.F.S);
        int d1=get_dist(r1, i.F.F);
        int d2=get_dist(r2, i.F.S);
        int h1=d1+get_dist(r2, i.F.F)-dis2[r2]+1;
        int h2=d2+get_dist(r1, i.F.S)-dis2[r2]+1;
        int mk1=d1;
        int mk2=d-d2;
        if(mk1>=mk2||mk1>=d-h2||mk2<=h1)ans=min(ans, nd-d1-d2);
        else ans=min(ans, nd-d1-d2-mk2-mk1+1);
    }
    printf("%d", ans);
}

Compilation message

Main.cpp: In function 'int main()':
Main.cpp:58:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   58 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
Main.cpp:61:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   61 |         scanf("%d %d %d", &a, &b, &c);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0.0 / 1.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Correct 10 ms 12032 KB Output is correct
3 Incorrect 9 ms 12032 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #2
0.0 / 2.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Correct 10 ms 12032 KB Output is correct
3 Incorrect 9 ms 12032 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #3
2.0 / 2.0

# 결과 실행 시간 메모리 Grader output
1 Correct 19 ms 13184 KB Output is correct
2 Correct 18 ms 13312 KB Output is correct
3 Correct 20 ms 13184 KB Output is correct
4 Correct 15 ms 13184 KB Output is correct
5 Correct 18 ms 13184 KB Output is correct
6 Correct 14 ms 13172 KB Output is correct
7 Correct 19 ms 13312 KB Output is correct
8 Correct 23 ms 13184 KB Output is correct
9 Correct 19 ms 13312 KB Output is correct
10 Correct 15 ms 13184 KB Output is correct
11 Correct 16 ms 13184 KB Output is correct
12 Correct 15 ms 13184 KB Output is correct
13 Correct 20 ms 13184 KB Output is correct
14 Correct 16 ms 13184 KB Output is correct

Subtask #4
0.0 / 6.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Correct 10 ms 12032 KB Output is correct
3 Incorrect 9 ms 12032 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #5
0.0 / 2.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Correct 10 ms 12032 KB Output is correct
3 Incorrect 9 ms 12032 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #6
0.0 / 3.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Correct 10 ms 12032 KB Output is correct
3 Incorrect 9 ms 12032 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #7
0.0 / 5.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Correct 10 ms 12032 KB Output is correct
3 Incorrect 9 ms 12032 KB Output isn't correct
4 Halted 0 ms 0 KB -

Subtask #8
0.0 / 4.0

# 결과 실행 시간 메모리 Grader output
1 Correct 9 ms 12032 KB Output is correct
2 Correct 10 ms 12032 KB Output is correct
3 Incorrect 9 ms 12032 KB Output isn't correct
4 Halted 0 ms 0 KB -